A/C pressure switch - quick diagnosis

Discussion in '80-Series Tech' started by harrydunn, Jun 22, 2010.

  1. harrydunn

    harrydunn

    Messages:
    882
    Location:
    Columbia, Missouri
    Now that we're in the 90's here in central-MO, I figured I'd take a look at my A/C system and troubleshoot why the compressor clutch is not kicking in.

    After searching the forums and consulting my FSM, I jumpered the pressure switch and that did the trick. Clutch engaged & RPM's jumped up. Should I continue with more troubleshooting or is this a sure sign I'm simply low on Freon? I only ran it 20 seconds or so but never saw anything in the sight glass. This is not my daily driver so I'm not looking to spend too much on the A/C. However, if it simply needs refrigerant, I'd definitely pony up for that.

    Thanks,

    Mark

    [​IMG]
  2. superjuice

    superjuice SILVER Star

    Messages:
    651
    Location:
    CT
    Have you converted to r134a or is it still r12, i ask because your probably low on "freon" and thats why the pressure doesnt build up high enough to activate the compressor. I would guess you need to get it recharged. 134a is available in a do it yourself kit at walmart/autoparts store (stay away from the stop leak stuff). r12 is a bit difficult to get a hold of from what i've read, but it can be done at a licensed shop. HTH
  3. harrydunn

    harrydunn

    Messages:
    882
    Location:
    Columbia, Missouri
    I'll have to check the cap colors tonight to see what it's running.
  4. harrydunn

    harrydunn

    Messages:
    882
    Location:
    Columbia, Missouri
    I'm know nothing about A/C systems, but I checked it out and there are screw-on type caps on the compressor connections (Schrader valve caps like on a car tire), so I'm assuming I'm still running R12, as the sticker on my radiator support says. I see no evidence of a new R134a sticker affixed anywhere.

    I still have options but I don't like them as much as my R134a options, had it already been converted.
  5. Michael Hanson

    Michael Hanson

    Messages:
    7,381
    Location:
    Plano texas
    e-bay r-12 10.00 a can. MIke
  6. harrydunn

    harrydunn

    Messages:
    882
    Location:
    Columbia, Missouri
    Will most shops still work with R12 if I were to obtain some cans? I'd probably rather just have somebody else do it since I do not have any of the equipment. Not sure how interested they would be in working with me if I brought in my own cans compared to their much more expensive R12.

    Thanks.

    --Mark
  7. harrydunn

    harrydunn

    Messages:
    882
    Location:
    Columbia, Missouri
    R12 charge went well. Reading 40 degrees at the vents. I'm sure others have reported colder temps but it's plenty chilly for me. Far left vent is not kicking any air out so I need to troubleshoot that. I'm wondering if the open/close linkage is busted for that particular vent.

    --Mark

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